The pair were loaned to the RZSS charity as part of a 10-year arrangement with the China Wildlife Conservation Association, but will now return to China at the end of 2023.
Tian Tian gave birth to a cub in 2007 before she came to Scotland, but efforts to breed from the pair in Edinburgh have proved elusive.
A natural breeding attempt was made in 2012, with artificial insemination used instead each year between 2013 and 2017.
Tian Tian was believed to be pregnant in August 2017, but her hormone levels and behaviour later returned to normal. Phantom pregnancies are common among giant pandas.
She was artificially inseminated again in 2019 and April this year, but both were unsuccessful.
RZSS confirmed that breeding will not be attempted during the final two years of the pandas’ Edinburgh stay.
RZSS chief executive David Field said: “A cub would have generated even more interest in giant pandas and given Tian Tian a wonderful opportunity to be a mother again, after she gave birth in China.
“However, natural and artificial insemination breeding attempts have not been successful and now is the time to move on and just enjoy having Yang Guang and Tian Tian with us for two more years.
“We are very proud of the contribution we have made to giant panda breeding research alongside our partners at the University of Edinburgh, and our findings have been of real benefit to international efforts to protect the species.
“We are thrilled that Yang Guang and Tian Tian will be staying at Edinburgh Zoo for two more years.
“Yang Guang and Tian Tian have helped millions of people connect with nature, so it is fantastic that they will be with us a little longer before we say goodbye, especially as the pandemic has made it much harder for people to visit them.
“It is encouraging that the status of giant pandas in the wild has been moved by the IUCN from endangered to vulnerable thanks to conservation efforts in China,” he added.
“However, their conservation still faces many challenges, so we will continue to make a substantial annual donation to support this work while Yang Guang and Tian Tian remain with us.”
China has loaned pandas as a sign of goodwill to several nations, with any cubs born during their stay also considered property of China and must be returned to help further the national breeding programme.
The zoo said it plans to convert the giant panda habitat to suit a new species once the pair return to China.
Mr Field added: “Many other animals still face the threat of extinction and we are excited about working with a new species at the zoo.
“We will decide on the species over the next year, with a crucial factor being how we can support conservation in the wild.”
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